Chain saw question

[Henro]

I have a Stihl arborist saw M 192TC model. It starts and seems to run fine except for one thing.

If I pull the trigger all the way it wants to cut out. I mean, it loses power and the speed drops. If I hold the trigger at 90% or maybe 95% it runs at full speed and sounds totally normal.

I’m not sure what the message is here. Is this a common symptom of something?

I will check my air filter after posting this. Something I should’ve done first thing I think. Just getting this saw ready for first use after sitting during the winter, spring and at this rate most of the summer. The small Dewalt 20 volt battery chainsaw is too convenient for small jobs around the place.

 

[The Evil Twin]

First things I would check are:
Air filter, fuel filter, spark arrestor.

 

[Henro]

First things I would check are:
Air filter, fuel filter, spark arrestor.

Well, I’m embarrassed to say it. I cleaned the air filter and that solved the issue. Something I should’ve done before posting I realized as I was posting that, but since I typed it, I figured I better get some extra ideas just in case.

I guess my past experience must be nothing comes easy! But this time it did!

Thanks for your advice Evil Twin!

 

[The Evil Twin]

I often answer my own questions after I ask them.

 

[Flintknapper]

Well, I’m embarrassed to say it. I cleaned the air filter and that solved the issue. Something I should’ve done before posting I realized as I was posting that, but since I typed it, I figured I better get some extra ideas just in case.

I guess my past experience must be nothing comes easy! But this time it did!

Thanks for your advice Evil Twin!

IF you don't plan on using it on State/Federal land....ditch the spark arrestor. It will be the next thing to plug up and give you trouble.

 

[Henro]

IF you don't plan on using it on State/Federal land....ditch the spark arrestor. It will be the next thing to plug up and give you trouble.

Sounds like great advice! Now, if I can just figure out where the spark arrestor is…

 

[OntheRidge]

Sounds like great advice! Now, if I can just figure out where the spark arrestor is…

Don't get rid of the spark arrestor, your saw will over rev. It is the screen on the muffler, just clean it from time to time.. The saw is tuned to have it in place. I ran Stihls for 35 years as a pro arborist, old school saws were ok to remove, new tech not so much.

 

[Henro]

Sounds like great advice! Now, if I can just figure out where the spark arrestor is…

IF you don't plan on using it on State/Federal land....ditch the spark arrestor. It will be the next thing to plug up and give you trouble.

After reading Flintnappers post I did a search and came upon a really good, for me, YouTube video on my specific saw the MS 192TC.

The guy goes through the whole process of showing where everything is. I think that was perfect for me, but I don’t think he used logical troubleshooting techniques. But I really appreciate it because it showed me how to take everything apart and where everything was and all that sort of thing.

In the end, his problem was a dirty spark arrestor. His problem initially was about exactly what mine is. After cleaning my air filter, yesterday I ran a half tank of fuel before my problem came back. After the saw cooled down, it seemed to work normally again, but I also fiddle around with the fuel filter. Getting the fuel filter out of the tank is an experience because the fuel line connecting to the filter is so short you can hardly get the filter out of the tank for inspection. My fuel filter looked pristine.

Now that I know where the spark arrester is and how to access it, I’m going to follow Flintnappers suggestion, and just eliminate it. In the YouTube video, the guy cleaned it and it rectified his problem.

 

[Henro]

Don't get rid of the spark arrestor, your saw will over rev. It is the screen on the muffler, just clean it from time to time.. The saw is tuned to have it in place. I ran Stihls for 35 years as a pro arborist, old school saws were ok to remove, new tech not so much.

hummm… another piece of maybe practical advice.

So guys, what’s the verdict on my dilemma? Is perhaps a slight increase of RPM due to a decrease in exhaust flow resistance a real concern? I remember when I was a kid 60 years ago we did everything we could to reduce restrictions in exhaust systems on the cars of those days…

edit: also, I don’t use this saw much. If I used it 20 hours in a year, I would be patting my back with both hands multiple times!

 

[Henro]

hummm… another piece of maybe practical advice.

So guys, what’s the verdict on my dilemma? Is perhaps a slight increase of RPM due to a decrease in exhaust flow resistance a real concern? I remember when I was a kid 60 years ago we did everything we could to reduce restrictions in exhaust systems on the cars of those days…

edit: also, I don’t use this saw much. If I used it 20 hours in a year, I would be patting my back with both hands multiple times!

After reading Flintnappers post I did a search and came upon a really good, for me, YouTube video on my specific saw the MS 192TC.

The guy goes through the whole process of showing where everything is. I think that was perfect for me, but I don’t think he used logical troubleshooting techniques. But I really appreciate it because it showed me how to take everything apart and where everything was and all that sort of thing.

In the end, his problem was a dirty spark arrestor. His problem initially was about exactly what mine is. After cleaning my air filter, yesterday I ran a half tank of fuel before my problem came back. After the saw cooled down, it seemed to work normally again, but I also fiddle around with the fuel filter. Getting the fuel filter out of the tank is an experience because the fuel line connecting to the filter is so short you can hardly get the filter out of the tank for inspection. My fuel filter looked pristine.

Now that I know where the spark arrester is and how to access it, I’m going to follow Flintnappers suggestion, and just eliminate it. In the YouTube video, the guy cleaned it and it rectified his problem.

Forgot to add the link to that video. Might be helpful for anyone with a MS192TC that knows nothing like me!

 

[CGMKCM]

My opinion, I would take the saw to a Stihl dealer and have it serviced. I have seen fuel filters with a slim coating of slime from old fuel cause problems. Carb may be fouled from fuel or carb adjustment could cause problem. Ask about how to treat fuel system for long term storage.

 

[skeets]

Henro,, I have the same saw, and I have never had a such a hard pulling saw in my life. If I dont run it for a wile it feels like Im going to pull the rope out of the winder,, once it turns over a couple times, seems to loosen up but may or may not start,, worst saw I ever had, the old Husky was several times what this one is,,, oh well

 

[RCW]

IF you don't plan on using it on State/Federal land....ditch the spark arrestor. It will be the next thing to plug up and give you trouble.

When I used a saw a lot years ago - first thing to go was the spark arrestor.

Don't get rid of the spark arrestor, your saw will over rev. It is the screen on the muffler, just clean it from time to time.. The saw is tuned to have it in place. I ran Stihls for 35 years as a pro arborist, old school saws were ok to remove, new tech not so much.

Something I didn't consider with "modern" saws; many are now computerized. Mine are not, but I've looked at them to replace current arsenal.

Valid point. If I had an auto-tune or similar variation, I would heed this advice.

 

[DaveFromMi]

How long has it sat around with gas in it? Sometimes I get lucky and clean out the fuel system with a hefty dose of Sea Foam.
I have a nice little saw, MS 180, that only has one adjustment, idle speed. I've replaced the carb a few times.
Newer saws are made to run lean, so any gunk in the fuel system will shut them down

 

[Henro]

How long has it sat around with gas in it? Sometimes I get lucky and clean out the fuel system with a hefty dose of Sea Foam.
I have a nice little saw, MS 180, that only has one adjustment, idle speed. I've replaced the carb a few times.
Newer saws are made to run lean, so any gunk in the fuel system will shut them down

I dumped all the fuel out to eliminate the old fuel question. It ran well for a half a tank with new fuel so I don’t think the fuel condition is a problem. I agree that a visual inspection doesn’t necessarily tell the whole story when you look at the fuel filter. But in my case, I think the next logical thing to do is check and possibly eliminate the spark arrestor.

Easy enough to do and it seems like that’s the logical next step.

 

[lynnmor]

I have an older Stihl weed wacker that lost power so I took it to the selling dealer. He said it would be the spark arrestor screen and he would just be taking my money to do this simple job. After my second round of power loss I switched from the expensive Stihl oil and have used Ace hardware oil ever since and that ended the screen clogging. Just this spring I went over the unit and checked the screen which was clean. There is a YouTube video about the Stihl oil causing the problem, you actually don't get what you pay for.

 

[RCW]

I have an older Stihl weed wacker that lost power so I took it to the selling dealer. He said it would be the spark arrestor screen and he would just be taking my money to do this simple job. After my second round of power loss I switched from the expensive Stihl oil and have used Ace hardware oil ever since and that ended the screen clogging. Just this spring I went over the unit and checked the screen which was clean. There is a YouTube video about the Stihl oil causing the problem, you actually don't get what you pay for.

Really?!??!

Not disagreeing but thought the latest Stihl Synthetic was the best available.

My newer 4 cycle FS131 brushcutters recommend the synthetic to avoid build up on the valves. They even double the warranty if buying the new oil with a trimmer.......

Used it in my old (1991) FS86 too, but ethanol gas got that. My fault on that one.

Been using in my older chainsaws as well, so interested/curious...

Thanks.

 

[The Evil Twin]

If you are having to clean the spark arrestor too often, you should consider different fuel and/ or oil. Or even your measuring method.

 

[OntheRidge]

Really?!??!

Not disagreeing but thought the latest Stihl Synthetic was the best available.

My newer 4 cycle FS131 brushcutters recommend the synthetic to avoid build up on the valves. They even double the warranty if buying the new oil with a trimmer.......

Used it in my old (1991) FS86 too, but ethanol gas got that. My fault on that one.

Been using in my older chainsaws as well, so interested/curious...

Thanks.

Yes, there is a youtube video by Chickanic where she talks about the Stihl oil.

 

[CGMKCM]

I am not an expert so your results may be different.
I have taken classes in small engine maintenance and repair and I service/ maintain numerous two stroke and 4 stroke pieces of equipment. Stihl synthetic 2 stroke oil is fine if you always run wide open throttle and burn through fuel vs. long term fuel storage.

Several videos on YouTube of Stihl synthetic oil causing problems in storage and run at lower throttle positions. Stihl states that oil is bio-degradable and there is debate about what that can lead to in lower throttle output and storage.

I run Echo Red Armor at 40:1 with premium non ethanol gasoline and mix 2.5 gallons at a time. I agree that Chickanic, Mower Medic, Tarral and several other small engine mechanics are good sources of information on YouTube.